This invention pertains to bicycle pedals, to the types of bearings used in bicycle pedals, and to the ways in which they are mounted on the pedal spindles.
Currently, most bicycle pedals use cup-and-cone bearings in which ball bearings are supported on cones on the spindle and in bearing cups in the pedal bodies. The outboard cone is usually adjustable. The spindles are usually solid members, made as lightly as possible, consistent with the need for strength and rigidity.
A bicycle pedal spindle is essentially a cantilever beam, having a circular cross section, which is loaded near its end. Since most of the load is carried on or near the outside surface of such members, it follows that pedal spindles should ideally be tubular or hollow, for maximum strength and rigidity with minimum weight. While some pedals have appeared which had spindles with axial holes drilled through them to lighten them without significantly reducing their strength or rigidity, very few have been produced with hollow, tubular spindles with thin walls.
Also, while a few pedals have appeared using modern bearings, it is true that few current bicycle pedals employ newer, improved bearings. One such bearing is the drawn-cup needle roller bearing.
In such bearings, steel rollers are retained by tubular cups which are rolled over at their ends, and the rollers are spaced apart and kept parallel to each other by light steel bearing cages. Such bearings are available with neoprene seals.
Because of their high radial capacity, light weight, guiding cages, neoprene seals, low cost, and ease of installation, drawn cup needle roller bearings are ideal inboard bearings for bicycle pedals, and they are particularly suitable for use with hollow tubular pedal spindles, because they can roll directly on such pedal spindles, without having inner races.
Another bearing which has never seen much use in bicycle pedals is the Conrad-type ball bearing having inseparable races.
Such ball bearings have relatively deep grooves and high carrying capacities in both radial and axial directions; they are ideal outboard bearings for bicycle pedals.
If the two bearings can be fitted into a straight bore through a pedal body, the pedal body is less expensive to make. However, if this is done, the inside diameter of the ball bearing is much smaller than the inside diameter of the drawn-cup needle roller bearing it is to be paired with; one of the problems addressed by the current invention is how to economically mount a Conrad bearing having a relatively small inside diameter onto the large open end of a tubular pedal spindle.
Also, since a tubular spindle would be heat treated to provide the required case and core hardnesses, and any subsequent heating might adversely affect such hardening, an outboard bearing mounting which required no further heating of the spindle, such as would occur if the spindle were annealed, welded, or brazed, would be of advantage. This is another problem addressed by the current invention.